Optical disk discriminating method and optical disk reproducing method and optical disk device

ABSTRACT

The requested data is read from a DVD disk by interruption in ST 46.  Then, the ID information for indicating the leading end of the data, and the result of the identification by use of the EDC for indicating whether or not the data is correct are stored in ST 47.  When the disk is identified as a DVD-video disk and the flag is set in ST  48,  and also when the number of times N of retries is identified as being larger than NR in ST 50  and the read data is not identified as control data in ST 51,  data transmission is performed. When no flag is set, the disk identification is performed based on whether or not the data at a predetermined position on the logical format has predetermined data in ST 49.  When it is identified that an error has been detected in ST 52  and also when the number of times N of retries becomes larger than NS in ST 53,  the occurrence of an error is announced.

FIELD OF THE INVENTION

[0001] The present invention relates to a method for identifying opticaldisks suitable for the case of using plural kinds of optical diskshaving physical specifications identical to each other, a method forreproducing optical disks, and an optical disk apparatus.

BACKGROUND ART

[0002] In recent years, as technology relating to optical disksprogresses, there have been suggested optical disks having physicalspecifications identical to each other, and having contents of recordedsignals different from each other. For example, as a compact disk, ontop of a CD-DA in which music data is recorded, also suggested are diskssuch as a CD-ROM in which computer data and the like is recorded, and avideo CD (i.e. a compact disk) in which images (i.e. video images),sounds, and the like are recorded. In addition, as an optical diskcalled as a digital versatile disk (DVD) which has a high recordingcapacity attained by giving a recording density higher than that of acompact disk, suggested are a DVD-ROM in which computer data isrecorded, a DVD-Video in which images and sounds of movies are recorded,and the like.

[0003] A CD-ROM is constituted by giving a CD-DA an ability of recordingan error correction code into the data zone of the sector, and by use ofthe error correction data, the CD-ROM has an increased ability of errorcorrection as compared with the CD-DA. In this structure, when a CD-ROMdecoding circuit for performing error correction using theabove-described error correction code is provided to a disk reproducingapparatus for obtaining a reproduction output signal by reading a signalrecorded in the CD-DA and then by demodulating the read signal, both theCD-DA and the CD-ROM can be reproduced in a single disk reproducingapparatus. The video CD records video and audio data compressed incompliance with the Moving Picture Experts Group (MPEG) 1 standards, byuse of a physical format of the CD-ROM XA which has been established byexpanding the CD-ROM standards. In this structure, when an MPEG decodercircuit for decoding the compressed data is further provided to the diskreproducing apparatus, not only a CD-CA and a CD-ROM but also a video CDcan be reproduced in a single disk reproducing apparatus.

[0004] In a disk reproducing apparatus for reproducing a DVD disksimilarly, when an MPEG decoder circuit for decoding video and audiodata compressed in compliance with the Moving Picture Experts Group(MPEG) 2 standards is provided to a DVD-ROM disk reproducing apparatusfor obtaining a reproduction output signal by reading a signal recordedin the disk and then by performing demodulation and error correction forthe signal, not only a DVD-ROM disk but also a DVD-Video disk can bereproduced in a single disk reproducing apparatus.

[0005] In the above-described optical disks, in the cases where theoptical disks themselves have defects, where scratches are created onthe optical disks, or where dusts are attached on the optical disks,possibilities arise that the data recorded therein may not be readcorrectly, due to the influences of the defects, scratches, dusts, andthe like. If such troubles occur in the case where the recorded data iscomputer data, it is desirable to repeat retry where the recorded datais read again, so as to obtain data as correct as possible. However, ifthe recorded data is video data or audio data, and the retry is repeatedin an attempt to obtain correct data, the period in which the data isnot read become longer, resulting in discontinuity of the images andsounds.

[0006] In such situations, the present invention provides a method foridentifying optical disks in which the kind of data recorded in each ofthe optical disks is identified and a reproducing operation is performedin accordance with each of the optical disks, a method for reproducingoptical disks, and an optical disk apparatus.

DISCLOSURE OF THE INVENTION

[0007] A method for identifying optical disks of the present inventionincludes the step of: in a state where each the optical disks isreproduced, performing identification of the optical disk, based onwhether or not data at a predetermined position on a logical format in adata zone has predetermined data.

[0008] Each of the optical disks is reproduced in a predeterminedsequence, and the identification of the optical disk is performed whenthe data at the predetermined position on the logical format isreproduced. The data at the predetermined position is data in a unit ofblock, and the predetermined data is data of a error correction codecompleted within the block.

[0009] The data at the predetermined position is data in a predeterminedfile structure recorded in each of the optical disks, and thepredetermined data is data related to contends of the recorded data. Amethod for reproducing optical disks according to the present inventionincludes the steps of: performing identification of each of the opticaldisks, based on whether or not data at a predetermined position on alogical format in a data zone obtained by reproducing the optical diskhas predetermined data; and controlling a reproducing operation based ona result of the identification.

[0010] When an error is detected in the data obtained by reproducingeach of the optical disks, a processing for responding to the errordetection is switched based on the result of the identification.

[0011] Retry for reading data from each of the optical disks again isperformed in the processing for responding to the error detection. Thenumber of times of the retries or the period of time for the retriesperformed until correct data is obtained is switched based on the resultof the identification. When the data in which an error has been detectedis control data related to an operation, the switching of the processingfor responding to the error detection is cancelled.

[0012] A speed of reading data from each of the optical disks or anamount of data read from each of the optical disks beforehand isswitched based on the result of the identification.

[0013] An optical disk apparatus according to the present inventionincludes: data reading means for, in a state where each of optical disksis reproduced, reading data recorded therein; and control means foridentifying the optical disk based on whether or not data which has beenobtained by the data reading means and is located at a predeterminedposition on a logical format in a data zone has predetermined data, andfor performing control on an operation in accordance with a result ofthe identification.

[0014] The optical disk apparatus includes: error detection means fordetecting an error of the data obtained by the data reading means,wherein when the error is detected by the error detection means, thecontrol means switches processing for responding to the error detectionbased on the result of the identification.

[0015] The control means controls the data reading means based on theresult of the identification in such a manner as to switch a speed atwhich data is reading from each of the optical disks, or controls thedata reading means in such a manner as to switch an amount of data to beread forehand from each of the optical disks, based on the result of theidentification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a diagram showing a structure of a compact disk.

[0017]FIG. 2 is diagram showing a frame structure of a CD signal.

[0018]FIG. 3 is a diagram showing a structure of a subcode Q.

[0019]FIGS. 4A to 4D are diagrams each showing a data structure in ablock.

[0020]FIG. 5 is a diagram showing a disk structure of a CD-ROM.

[0021]FIG. 6 is a diagram showing a disk structure of a video CD.

[0022]FIGS. 7A to 7D are diagrams each for illustrating compressed datato be recorded in a truck.

[0023]FIG. 8 is a flow chart showing retry.

[0024]FIG. 9 is a diagram showing a structure of a subheader.

[0025]FIG. 10 is flow chart showing another retry.

[0026]FIG. 11 is a diagram showing a structure of a disk reproducingapparatus.

[0027]FIG. 12 is a flow chart showing an operation of setting retry.

[0028]FIG. 13 is a flow chart showing the processing of confirming videoCD identification information.

[0029]FIGS. 14A and 14B are diagrams each showing an example of dataread from the sector at the position of 4.00 seconds.

[0030]FIG. 15 is a diagram showing a structure of a header.

[0031]FIG. 16 is a diagram showing a physical sector number of a DVDdisk.

[0032]FIG. 17 is a diagram showing a directory structure.

[0033]FIG. 18 is a diagram showing a data structure of UDF Bridge.

[0034]FIG. 19 is a diagram showing a structure of a disk reproducingapparatus.

[0035]FIG. 20 is a flow chart showing a data reproducing operation.

[0036]FIG. 21 is a flow chart showing data identification.

[0037]FIG. 22 is a diagram showing a part of the data stored in a RAM.

BEST MODE FOR CARRYING OUT THE INVENTION

[0038] Hereinafter, the present invention will be described withreference to the drawings. FIG. 1 is a diagram showing a structure of anoptical disk, for example, of a compact disk. At an inner peripheralside of the disk, a lead-in zone is formed, and at an outer peripheralside thereof, a lead-out zone is formed. The zone between the lead-inzone and the lead-out zone is a data zone.

[0039] Here, one frame of a CD signal recorded in the compact disk isconstituted by a frame synchronous signal and a subcode, and data and aparity, as shown in FIG. 2. The subcode is in 8 bits from P channels toW channels, and one subcode frame is constituted by the CD signal of 98frames. In the subcode frame, first two CD signal frames are defined asa synchronous signal Sync-0 and Sync-1, and the remaining 96 frames areused to indicate information.

[0040] As shown in FIG. 3, the Q channels of the subcode (hereinafter,referred to as a “subcode Q”) include a control field (Q0 to Q4), anaddress field (Q4 to Q7), a data field (Q9 to Q80), and a CRC field (Q81to Q96).

[0041] The control field shows information for identifying whether therecorded signal is audio data or digital data, information foridentifying the number of audio channels, information whether anemphasis is present or absent, and the like. For example, for the2-channel audio having no pre-emphasis, its control field is defined as(0000). For a disk in which digital data is recorded, for example, in aCD-ROM, its control field is defined as (01x0 (where x is 0 or 1).

[0042] The address field shows the contents of information that the datafield subsequent to the address field has. The data field showsinformation associated with the address field. For example, when theaddress field is defined as (0001), the data field shows a truck number,an elapsed time, an absolute time, and the like. When the address fieldis defined as (0011), the data field shows an international standardrecording code (an ISR code). The CRC field is provided with paritybits. In the lead-in zone shown in FIG. 1, the truck number TR indicatedby the data field is defined as “00”, while in the lead-out zone, thetruck number TR is defined as “AA”.

[0043] When the compact disk is a CD-ROM, as shown in FIG. 2, the datazone is arranged to include the CD signal of 98 frames, that is, 2352bytes are set to 1 block, and the signal is recorded in units of theseblocks.

[0044] In the CD-ROM, as shown in FIG. 4, the data structure within theblock is categorized into three modes from mode 0 to mode 2, dependingon the kind of the data to be recorded. The mode 0 shown in FIG. 4A isused as a dummy block in the case where the lead-in zone and thelead-out zone are provided with the CD-ROM structure. A first 12byte-area in the block constitutes a synchronous signal for sorting theblock, and a next 4 byte-area is used as a header area. The remaining2336 byte-area is entirely defined as “0”.

[0045] The mode 1 shown in FIG. 4B is used for recording data. The 2048byte-area subsequent to the header area is used as a user data area. Aremaining 288 byte-area is used as an auxiliary data area in which anerror correction code completed within the block is recorded.Specifically as shown in FIG. 4B, a cyclic redundancy code (CRC) whichis an error detection code, and a parity which is an error correctioncode are recorded in the auxiliary data area, so as to enable the errordetection and correction in the 2340 byte-area except for thesynchronous signal. In this manner, not only the cross interleavereed-solomon code (CIRC) but also the error correction code completedwithin the block (layered ECC) are provided, resulting in decreasing thebit error ratio to about 10-12.

[0046] In the mode 2, the 2336 byte-area subsequent to the header areais opened as a user data area. In the CD-ROM XA standards which enableinterleave between computer data and video or audio data, a form 1 and aform 2 are prepared for the mode 2. In the form 1 of the mode 2 shown inFIG. 4C, the 8 byte-area subsequent to the header area is defined as asubheader area, and the 2048 byte-area subsequent to the subheader areais defined as a data area into which computer data is recorded. A 280byte-area subsequent to the data area is defined as an auxiliary dataarea into which an error correction code completed within the block isrecorded. In the form 2 of the mode 2 shown in FIG. 4D, an 8 byte-areasubsequent to the header area is defined as a subheader area, and the2324 byte-area subsequent to the subheader area is defined as a dataarea for video and audio data. A 4 byte-area subsequent to the data areais defined as a reserved area.

[0047] In the CD-ROM, in order that the recorded data can be readwithout depending on the operating system of the computer apparatus, adisk structure shown in FIG. 5 and standardized as the internationalorganization for standardization (ISO) 9660 is employed.

[0048] In the data zone provided between the aforementioned lead-in zoneand the lead-out zone, the data of the information to be recorded isprovided with logical block numbers (LBNs) in units of 2 k bytes. Theposition of the first LBN “0” is defined as a position where the pregapof 150 sectors (corresponding to 2 seconds of audio) have passed fromthe end position of the lead-in zone.

[0049] Since an area with LBNs “0” to “15” is used as system areas, thearea of the data recorded in the CD-ROM starts from LBN “16”.

[0050] In the area starting from LBN “16” and thereafter, a primaryvolume descriptor (PVD) is recorded. In the volume descriptor of PVD,recorded are information for identifying the type of volume descriptorand the file format, and information required for reproducing therecorded data such as the size of the logical block (LB), the size andaddress of “Path Table”, and “root directory record”.

[0051] Subsequent of the PVD, recorded are a path table for indicatingthe leading end of the directory file and a directory for indicating theleading position of the file and the like.

[0052] Next, description will be made on a video CD in which recorded isdata including the contents such as images and sounds and beingcompressed in compliance with the moving picture experts group 1standards in the format of the CD-ROM XA standards.

[0053] In the video CD, as shown in FIG. 6, the area with the trucknumber TR=“01” subsequent to the lead-in zone includes a PVD and aKaraoke information section, a video CD information section, a segmentplay section, and a CD-I application section. In the area with the trucknumber TR=“02” and thereafter, video and audio signals are recorded in acompressed state. In the area with the truck number TR=“01”, data isrecorded in the form 1 of the mode 2, and in the area with the trucknumber TR=“02” and thereafter, compressed data is recorded in the form 2of the mode 2.

[0054] The video CD information section is an area in which variouskinds of disk information and the like are recorded, and is constitutedby “INFO. VCD” in 1 sector (user data of 2 k bytes), “ENTRIES. VCD” in 1sector, “LOT. VCD” in 32 sectors, and “PBC. VCD” in 256 sectors at themaximum.

[0055] In the “INFO. VCD”, information about disk, information about asegment play item which will be described later, and the like arerecorded. In the “ENTRIES. VCD”, the entry number for indicating theposition from which the video or audio data recorded in the truck numberTR=“02” and thereafter is reproduced. Five hundreds of entries can beset at the maximum. In the “LOT. VCD”, a table for indicating theaddress of the list corresponding to the reproduction sequence isrecorded. In the “PBC. VCD”, a list of reproduction sequence isrecorded.

[0056] In the area with the truck number TR=“02” and thereafter, asshown in FIG. 7A, a front margin area of 15 sectors is provided at theposition in 150th sector (the index number “00”) counted from theleading end of the truck, and a rear margin area in 15 sectors countedfrom the last end is provided. The area located between the front marginarea and the rear margin area is defined as a compressed data area inwhich compressed video and audio data is recorded. In addition, in thecompressed data area, as shown in FIG. 7B, the compressed video data andthe compressed audio data are recorded in an interleaved manner so thatthe ratio between the sectors VS of the compressed video data and thesectors AS of the compressed audio data becomes about 6:1 on an average.The transmission rate of the video data is set to about 1.2M bit/second,and the transmission rate of the audio data is set to about 0.2bit/second.

[0057]FIG. 7C shows the format of the sector VS of the compressed videodata. The 2324 byte-data of 1 sector is recorded in the optical disk asdata in the data area in the form 2 of the mode 2 shown in FIG. 4D. Thesector VS of the compressed video data is constituted by a pack headersection and a packet section, and the video data area provided to thepacket section is used as an area for the compressed video data. Thepack header includes a start code of the pack header, a system clockreference SCR, and the like. The packet header of the packet sectionincludes a start code, an ID, a presentation time stamp PTS, a decodingtime stamp DTS, and the like. The STD buffer is provided to only theleading packet.

[0058]FIG. 7D shows the format of the sector AS of the compressed audiodata. As is the case of the compressed video data, the 2324 byte-data of1 sector is recorded in the optical disk in the form 2 of the mode 2.Similar to the sector of the compressed video data, the sector of thecompressed audio data is constituted by a pack header section and apacket section. The audio data area provided to the packet section isused as an area for the compressed audio data. The pack header sectionincludes a start code for pack header, a system clock reference SCR, andthe like. The packet header of the packet section includes a start code,an ID, a presentation time stamp PTS, a decoding time stamp DTS, and thelike.

[0059] At the time of reproducing the compressed video data and thecompressed audio data recorded in the optical disk, the images and thesounds are synchronized with each other using the system clockreferences SCR, the presentation time stamps PTS, the decoding timestamps DTS provided in the sector VS of the compressed video data andthe sector AS of the compressed audio data respectively.

[0060] If there arises a trouble that the recorded signal cannot be readcorrectly due to the defects, scratches, or attachment of dusts on thedisk during the reproduction of the compact disk structured as describedabove, the zone from which the signal cannot be read is subjected to aretry where the reading of the signal is tried again, thereby enablingthe signal in a correct manner. In addition, the retry performsprocessing which corresponds to the data recorded in the compact disk.For example, when the recoded data is computer data, the retry performsprocessing which puts importance to obtaining correct data. When therecorded data is video or audio data, the retry performs processingwhich puts importance to keeping continuity of the operations, whileallowing some lacks of data in order to prevent the images and soundsfrom being interrupted. Hereinafter, the retry for performing processingwhich puts importance to obtaining correct data is referred to as anormal retry, and the retry for performing processing which putsimportance to keeping continuity of the operations is referred to as asimplified retry.

[0061]FIG. 8 is a flow chart showing a retry. When the recorded signalcannot be read correctly, the retry is performed and then the procedureproceeds to Step ST1. in Step ST1 it is identified whether or not thedata for performing the retry has an error correction code completedwithin the block.

[0062] In this case, when an auxiliary data area is prepared and aparity and the like is recorded therein, the data is identified as datahaving an error correction code completed within the block, and theprocedure proceeds to Step ST2. Contrarily, when the data is identifiedas data having no error correction code completed within the block, theprocedure proceeds to Step ST3.

[0063] In Step ST2, the data recorded in the compact disk is identifiedas data required to have high reliability such as computer data, becausethe recorded data has enhanced error correction ability. In this case, anormal retry is performed. In the normal retry, the number of times ofretries N performed until the recorded data can be read correctly is setto a predetermined number of times NE or smaller. If it is impossible tocorrectly read the recorded data even after the reading is repeated inNE times, the occurrence of an error is announced and the retry isfinished without transmitting the data which has not been identified ascorrect data. The repeating of the reading may be limited by a period oftime, instead of the number of times. The reading may be repeatedtogether with the processing for facilitating the reading of therecorded data, for example, the processing for lowering the rotationspeed of the disk during the high-speed reproduction so that the datacan be easily read.

[0064] In Step ST3, the data recorded is identified as data not requiredto have high reliability unlike computer data, and is data required toput importance to keep continuity of the operation, that is, to keepingthe transition rate of the data, because the recorded data has no errorcorrection code completed within the block. In this case, a simplifiedretry is performed.

[0065] In the simplified retry, the maximum number of times N of retriesis set to a predetermined number of times NF which is smaller than thepredetermined number of times NE. When the repeating of the reading islimited by a period of time, the time limit is set to be shorter thanthe time limit employed in the normal retry. Alternatively, the readingof the data may be repeated as far as the transition rate of the data isnot excessively lowered to interrupt the images and sounds. If therecorded data cannot be read correctly, the retry is performed in thestate where the data which has not been identified as correct data isalso transmitted.

[0066] As described above, when the data has an error correction datacompleted within the block, a normal retry is performed. When the datahas no error correction data completed within the block, a simplifiedretry is performed. In this manner, the data required to have highreliability such as computer data is subjected to retry in whichpriority is attached to reading the data correctly. If it is impossibleto read the data correctly, the occurrence of an error is announced. Asa result, only correct data can be output. In addition, the probabilityof reading the data in a correct manner can be increased by increasingthe predetermined number of times NE. Contrarily, when the data isrequired to attach priority to keeping the transition rate such as videodata and audio data, a retry in which priority is attached to keepingcontinuity is performed. As a result, the data can be reproduced withoutinterrupting images and sounds.

[0067] The aforementioned CD-ROM XA standards allow the coexistence ofthe computer data, and video and audio data. In the mode 2 shown in FIG.4C and FIG. 4D, a subheader is provided. As is shown in FIG. 9, in thesubheader, 4-byte header information including a file number, a channelnumber, submode information for allowing identification whether the formis form 1 or form 2, is recorded twice repeatedly. Next, descriptionwill be made on the case where an optimum retry suitable of the recordeddata is performed by use of the subheader.

[0068]FIG. 10 is a flow chart showing the retry performed by use of thesubheader. When the recorded signal cannot be read correctly and theretry is performed, the procedure proceeds to Step ST11. In Step ST11,it is identified whether or not the sector of the data to be subjectedto the retry has the subheader. If the sector of the data is identifiedas having the subheader, the procedure proceeds to Step ST12.Contrarily, if the sector of the data is identified as having nosubheader, the procedure proceeds to Step ST14.

[0069] In Step ST12, it is identified whether or not the data is in theform 2, based on the submode information of the subheader. When the datais identified as being in the form 2, the procedure proceeds to StepST13. Contrarily, when the data is identified as being not in the form2, the procedure proceeds to Step ST14.

[0070] In Step ST13, since the data is recorded in the form 2 of themode 2, and has no error correction code completed within the block, therecorded data is identified as data required to attach priority tomaintaining the transition rate to keep continuity, rather than highreliability. In this case, the simplified retry is performed.

[0071] When the procedure proceeds from Step ST11 or Step 12 to StepST14, in Step ST14, the recorded data is identified as data not requiredto attach priority to maintaining transition rate to keep continuity,that is, as data required to have high reliability. In this case, thenormal retry is performed.

[0072] As in the manner described above, the use of the subheader alsomakes it possible to perform retry optimum for the recorded data.

[0073] In the flow chart shown in FIG. 8 and FIG. 10, when the retry isperformed, it is identified whether or not the data has an errorcorrection code completed within the block, or it is identified whetherthe retry should be set to the normal retry or the simplified retry,based on the subheader. In these cases, if the information about thesector to be subjected to the retry cannot be read correctly due to thedefects on the disk and the like, there is a fear that erroneousidentification is made. To avoid such a trouble, it may be identifiedwhether the data has an error correction code completed within theblock, by use of the information about the sector from which the datahas been read correctly immediately before the retry is performed, oralternatively, it may be identified whether the retry should be set tothe normal retry or the simplified retry, based on the subheader in thesector from which the data has been read correctly.

[0074] When the processing of the flow chart shown in FIG. 8 isperformed in the case where it is identified that no subheader ispresent in Step ST11, it is possible to set the retry to either thenormal retry or the simplified retry, depending on whether or not thedata has an error correction code completed within the block even forthe compact disk having no subheader.

[0075] In the aforementioned embodiment, when the recorded signal cannotbe read correctly and the retry is performed during the reproduction ofthe data, the retry is set to either the normal retry or the simplifiedretry. In a compact disk reproducing apparatus capable of reproducingvarious kinds of compact disks, when a compact disk is mounted to thedisk reproducing apparatus for example, the kind of the compact disk isidentified among the compact disks including a CD-DA, CD-ROM, video CD,and the like is made, by use of the information recorded in the compactdisk. Then, based on the result of identification of the disk, a signalprocessing operation suitable for the kind of the disk is performed tooutput a correct reproduction signal. In this structure, it may bedetermined whether the retry should be set to the normal retry or thesimplified retry, based on the result of the disk identification.

[0076]FIG. 11 shows a structure of a disk reproducing apparatus capableof reproducing not only a CD-DA but also a CD-ROM and a video CD. Acompact disk 10 is rotated at a predetermined speed by the spindle motorsection 32. The spindle motor section 32 is driven in such a manner thatthe compact disk 10 is rotated at a predetermined rotation speed, basedon a spindle control signal SP from a servo controlling section 24 whichwill be described later.

[0077] The compact disk 10 is irradiated with a light beam in acontrolled light amount from an optical pickup 21. The light beam isreflected by the compact disk 10, and then is irradiated to aphotodetecting section (not shown) in the optical pickup 21. Thephotodetecting section performs photoelectric conversion andcurrent-voltage conversion, based on the reflected light beam to producea voltage signal at a signal level corresponding to the light amount ofthe reflected light beam, and then supplies the resultant voltage signalto an RF amplifying section 22.

[0078] The RF amplifying section 22 produces a read signal SRF by use ofthe voltage signal from the optical pickup 21, and then supplies theresultant read signal SRF to a CD signal processing section 23. The RFamplifying section 22 also produces a tracking error signal STE and afocus error signal SFE, and supplies the resultant tracking errorsignals STE and the focus error signal SFE to a servo controllingsection 24.

[0079] The servo controlling section 24 produces a focus control signalSFC for controlling an object lens (not shown) of the optical pickup 21in such a manner that the laser beam is focused to a position in therecording layer of the compact disk 10, based on the focus error signalSFE supplied thereto, and supplies the focus control signal SFC to adriver 25. The servo controlling section 24 also produces a trackingcontrol signal STC for controlling the object lens of the optical pickup21 in such a manner that the light beam is irradiated to a centerposition of a desired track, based on the tracking error signal STEsupplied thereto, and supplies the resultant tracking control signal STCto the driver 25. The servo controlling section 24 also produces athread drive signal SSL, and supplies the resultant thread drive signalSSL to a thread motor section 33 so as to drive the thread motor section33 to shift the optical pickup 21 toward a radial direction of thecompact disk 10.

[0080] The driver 25 produces a focus drive signal SFD based on thefocus control signal SFC, and also produces a tracking drive signal STDbased on the tracking control signal STC. Thus-produced focus drivesignal SFD and the tracking drive signal STD are supplied to an actuator(not shown) of the optical pickup 21, and as a result of this, theposition of the object lens is controlled so that the optical beamfocuses at a center position of a desired track.

[0081] The CD signal processing section 23 performs asymmetry correctionand binarization for the read signal SRF supplied thereto, and convertsthe read signal SRF into a digital signal. The CD signal processingsection 23 also performs EFM demodulation and CIRC reproduction toproduce a reproduction signal Daa. The CD signal processing section 23also supplies to a controlling section 35 the subcode informationrecorded in the compact disk 10 and the information recorded in apredetermined position in the compact disk.

[0082] When the controlling section 35, which will be described later,identifies the compact disk 10 as a CD-DA, the CD signal processingsection 23 outputs and supplies a reproduction signal Daa to an audiooutput section 26. The audio output section 26 converts the digitalreproduction signal Daa supplied from the CD signal processing section23, and a reproduction signal Dav supplied from a MPEG decoder 29 whichwill be described later into analog audio signals Sa, and outputs theresultant analog audio signals Sa. When the controlling section 35identifies the compact disk 10 as a CD-ROM or a video CD, the audiooutput section 26 supplies a reproduction signal Daa to a CD-ROM decoder27.

[0083] The CD-Rom decoder 27 performs decoding by use of an errorcorrection code completed within the block. When the controlling section35 identifies the compact disk 10 as a CD-ROM, the CD-ROM decoder 27performs decoding and supplies the signal obtained as a result of thedecoding to an external device via an interface 28 as a reproductionsignal Db. When the controlling section 35 identifies the compact disk10 as a video CD, the CD-ROM decoder 27 supplies the reproduction signalDb to an MPEG decoder 29.

[0084] The MPEG decoder 29 separates the signals of the video sectors VSand the signals of the audio sectors AS from each other, and then,decodes the compressed video data to produce a reproduction signal Dv.The MPEG decoder 29 also decodes the compressed audio data to produce areproduction signal Dav. Furthermore, the MPEG decoder 29 synchronizesthe video reproduction signal Dv and the audio reproduction signal Davwith each other and outputs them, by use of the system clock referenceSCR, the presentation time stamp PTS, the decoding time stamp DTS whichare recorded in the video CD. The video reproduction signal Dv issupplied to a visual output section 30, and simultaneously, the audioreproduction signal Dav is supplied to the audio output section 26. Thevideo output section 30 converts the reproduction signal Dv into a videooutput signal Svout in an NTSC mode and the like, and outputs theresultant signal.

[0085] To the controlling section 35, a manipulating section 36 and adisplaying section 37 are connected. When the manipulating section 36 isoperated to supply a manipulation signal PS to the controlling section35, the controlling section 35 controls each of the sections based onthe operation control program stored in a ROM 38 to operate the sectionsin accordance with the manipulation by the manipulating section 36. Thecontrolling section 35 also controls each of the sections based on thecommand supplied from an external device via an interface 28, forexample, a computer device.

[0086] The controlling section 35 also performs identification of thecompact disk, based on the subcode supplied from the CD signalprocessing section 23 and the information read from a predeterminedposition. Based on the result of the identification, the controllingsection 35 performs reproduction and outputs signals in accordance withthe kind of the compact disk. The controlling section 35 also produces adisplay signal HS and supplies it to the displaying section 37 tooperate the displaying section 37 to display the operating state of thedisk reproducing apparatus, the information read from the compact disk,and the like.

[0087] Hereinafter, the operation of setting the retry in the diskreproducing apparatus will be described, with reference to the flowchart of FIG. 12. when the compact disk 10 is mounted to the diskreproducing apparatus, in Step ST21, TOC information recorded in thelead-in zone is read. Then, the procedure proceeds to Step ST22.

[0088] In Step ST22, the controlling section 35 identifies whether thecompact disk 10 is a disk in which data is recorded, based on the datain the control field of the subcode Q which has been read together withthe TOC information. When the data in the control field is (01x0), andthe compact disk 10 is identified as a disk in which data is recorded,the procedure proceeds to Step ST 23. Contrarily, when the compact disk10 is not identified as a disk in which data is recorded, for example,when the data in the control field is (0000) as is the case of a CD-DA,the procedure proceeds to Step ST26.

[0089] In Step ST23, it is identified whether or not the video CDidentification information is recorded in the area with the track numberof TR=“01”. FIG. 13 is a flow chart showing a processing for confirmingthe video CD identification information.

[0090] In Step ST31, as shown in FIG. 6, data is read from the positionof 4.00 seconds (the logical block address LBA=96h (where h representshexadecimal notation)) which is a starting position of the video CDinformation section. Then, the procedure proceeds to Step ST32. In StepST32, it is identified whether the data has been read correctly. Whenthe data is read correctly, the procedure proceeds to Step ST33.Contrarily, when the data is not read correctly, the procedure proceedsto Step ST36.

[0091] In Step ST33, among the data read from the sector at the positionof 4.00 seconds, user information data of only 8 bytes counted from theleading end is obtained. FIG. 14 shows exemplary data read from thesector at the position of 4.00 seconds, in the state of eliminating thesynchronous signal therefrom. The first 4 bytes of the data constitute aheader. The constitution of the header is as shown in FIG. 15, that is,the first three bytes indicate a “minute, second, frame”, and the nextone byte indicates a mode segment. As has been described above, sincethe video CD information section is started from the position of 4.00seconds, the first 3 bytes of the header is defined as “00,04,00”. Thenext 1 byte indicates a mode segment. Since the mode segment has thedata of “02”, it is known that the data structure is in the mode 2. Whenthe data structure is in the mode 2, as shown in the aforementionedFIGS. 4C and 4D, a subheader is provided subsequent to the header.Therefore, the 8 bytes subsequent to the mode indication data indicatethe subheader. As shown in FIG. 9, in the subheader, 4-byte headerinformation is recorded twice repeatedly. In the case shown in FIG. 14A,the header information “00, 00, 89, 00” are repeated twice in thesubheaer. In the case shown in FIG. 14B, the header information “00, 01,88, 00” is repeated twice in the subheader.

[0092] The data subsequent to the subheader is user information for thevideo CD information section. The position corresponding to 13th bytecounted from the leading end is a starting position of the userinformation for the video CD information section. Specifically, in StepST33, the acquisition of the data is started from the positioncorresponding to the 13th byte counted from the leading end except forthe synchronous signal, and the acquisition of the data is finished atthe position corresponding to the 20th byte counted from the leadingend. In this manner, data of only 8 bytes from the leading end of thevideo CD information section can be obtained.

[0093] In the case of a video CD, as shown in FIG. 14, 8 bytes from theleading end of the user information of the video CD information sectionare defined as data “56, 49, 44, 45, 4F, 5F, 43, 44” for indicating apredetermined character string “VIDEO CD” as video CD identificationinformation. Therefore, in Step ST34, it is identified whether or notthe data obtained in Step ST33 is data of a predetermined characterstring, that is, data “56, 49, 44, 45, 4F, 5F, 43, 44” for indicating“VIDEO_CD”. In this manner, the presence or absence of video CDidentification information can be identified. In Step ST34, when thedata “56, 49, 44, 45, 4F, 5F, 43, 44” coincides with the data obtainedin Step ST33, it is assumed that the video CD identification informationis detected, and the procedure proceeds to Step ST35. When these data donot coincide with each other, it is assumed that no video CDidentification information is detected, and the procedure proceeds toStep ST36.

[0094] In Step ST35, since the video CD identification information hasbeen detected, the video CD identifying flag set to the register withinthe controlling section 35 is turned on, and the processing forconfirming the video CD identification information is finished. When theprocedure proceeds from Step ST32 or Step ST34 to Step ST36, since novideo CD identification information has been detected, the video CDidentifying flag is turned off, and the processing for confirming thevideo CD identification information is finished.

[0095] In Step ST23 in FIG. 12, it is identified whether or not thevideo CD identification information has been detected. At this time,when the video CD identifying flag is turned off by the processing shownin FIG. 13 and it is indicated that no video CD identificationinformation has been detected, the procedure proceeds to Step ST25. Whenthe video CD identifying flag is turned on and it is indicated that thevideo CD identification information has been detected, the procedureproceeds to Step ST26.

[0096] In Step ST25, a processing mode setting flag, provided within thecontrolling section 35, that is, a flag for setting the retry performedat the time when the data cannot be read correctly to the normal retryor the simplified retry, is set to the normal retry mode. When theprocedure proceeds from Step ST22 or Step ST24 to Step ST26, theprocessing mode setting flag is set to the simplified retry mode in StepST26.

[0097] After that, the compact disk 10 is reproduced in the diskreproducing apparatus. If there arises the case where the recorded datacannot be read correctly, the normal retry or the simplified retry isperformed based on the processing mode setting flag.

[0098] As in the manner described above, identification of the compactdisk is performed automatically at the time when the disk is mounted tothe apparatus. Based on the results of the identification, the retry isset to the normal retry or the simplified retry. Due to thisarrangement, it is possible to set the retry which attaches priority toreading data correctly when the data is required to have highreliability such as computer data. On the other hand, it is alsopossible to set the retry which attaches priority to keeping continuityof the data when the data is required to maintain its transition ratesuch as visual or audio data. As a result, it is possible to performretry optimized for the recorded data.

[0099] For the data required to maintain its transition rate such asvisual or audio data, a retry which attaches priority to keepingcontinuity is performed. In this case, the reproduction is continuouslyperformed even if the data is not correct. As a result, a video or audiooutput signal can be obtained even if an optical disk with poor qualityis reproduced.

[0100] The detection of the predetermined character string “VIDEO_CD” asthe video CD identification information is automatically performed inthe disk reproducing apparatus as described above. Alternatively, thedetection may be performed at the time when an external device such as ahost computer or a reproducing application makes a read request to thedisk reproducing apparatus for the purpose of disk identification. Inaddition, since the predetermined character string “VIDEO CD” as thevideo CD identification information is recorded at a predeterminedposition, the detection thereof is easy.

[0101] In the aforementioned embodiment, the mode of retry is selectedbased on the results of the compact disk identification. The results ofcompact disk identification may be also utilized in other operations.

[0102] It is assumed that the control on rotation of the spindle motoris switched, based on the results of the compact disk identification.For example, when the compact disk is identified as a video CD, theoperation is image reproduction which has no need of reading the data athigh speed. In this case, the disk is rotated at a normal speed, therebypreventing the electric power consumption from increasing and decreasingthe sounds created by the operations of the disk apparatus. When thecompact disk is identified as a CD-ROM, the data is read in the statewhere the disk is rotated at a speed higher than a normal speed, therebyincreasing the data transition rate. As a result, the data can beefficiently read from the CD-ROM when the data is processed in thecomputer apparatus.

[0103] It is possible to switch the amount of data which is readbeforehand based on the results of disk identification. As to a videoCD, there are many cases where the data recorded for use in reproducingimages and the like is sequentially read. Therefore, when the disk isidentified as a video CD, the amount of data which is read beforehand isincreased. In this manner, the read data can be efficiently processed,and in addition, the interruption of the images for example can beprevented. On the other hand, as to the CD-ROM, there are many caseswhere the data is read at random. In such cases, reading of the databeforehand may not be effective. There are also some cases where variouscontrol parameters are required in order to shorten the access time. Forthese reasons, the amount of data which is read beforehand is reduced.As a result, the data can be read efficiently, without readingunnecessary data.

[0104] In the aforementioned embodiment, description has been made as tothe case where the optical disk is a compact disk. Similarly, when theoptical disk is a DVD which has a high recording capacity by increasingthe recording density to be higher than that of a compact disk, thereproduction can be performed in accordance with the data recorded inthe disk.

[0105]FIG. 16 shows a physical sector number in a DVD. The zone from thephysical sector number “0h” at the innermost peripheral side of the diskto “2FFFFh” is defined as a lead-in zone for indicating a physicalspecification of the disk and information about the supplier ofcontents. The zone from the physical sector number “30000h” subsequentto the lead-in zone to the zone at the outermost peripheral side isdefied as a data zone. Data signals of contents are recorded in the datazone. At the outer peripheral side of the data zone, a lead-out zone forindicating the termination of the data zone is provided. The irradiatingposition of the light beam is made to be movable within the range fromthe lead-in zone to the lead-out zone.

[0106] As the file system employed in the DVD-ROM standards, employedare the International Organization for Standardization (ISO) 9660 whichis used as the standards for CD-ROM, and the universal disk format (UDF)which is usable in combination with the standards for a physical layernot only dedicated to reproduction but also capable of writing andrewriting. In order to satisfy both the standards, a file structurereferred to as “UDF Bridge” is employed.

[0107]FIG. 17 shows the file structure of “UDF Bridge”. In thisstructure, logical sector numbers (LSNs) from “0” to “15”, from “21” to“31”, and from “66” to “255” are defined as reserved areas. LSNs from“16” to “20” are defined as “UDF Bridge Volume Recognition Sequence(VSR)” areas. An LSN of “16” is defined as a “Primary VolumeDescriptor”. An LSN of “17” is defined as a “Volume Descriptor SetTerminator”. An LSN of “18” is defined as a “Beginning Extended AreaDescriptor”. An LSN of “19” is defined as an “NSR descriptor”. An LSN of“20” is defined as a “Terminating Extended Area Descriptor”. The“Primary Volume Descriptor” defined by the LSN of “16” is a volumedescriptor of a CD-ROM standardized by the ISO 9660. The “VolumeDescriptor Set Terminator” defined by the LSN of “17” indicates thetermination of the “Primary Volume Descriptor”. The “Beginning ExtendedArea Descriptor” defined by the LSN of “18” is a descriptor forindicating the beginning of an extended area. The “NSR Descriptor”defined by the LSN of “19” is a standard descriptor, and a descriptorindicated in the International Electrotechnical Commission (ISO/IEC)1344 is employed. The “Terminating Extended Area Descriptor” defined bythe LSN of “20” is a descriptor for indicating the termination of theextended area.

[0108] LSNs from “32” to “47” are defined as main VDS areas. An LSN of“32” is defined as a “Primary Volume Descriptor”. An LSN of “33” isdefined as an “Implementation Use Volume Descriptor”. An LSN of “34” isdefined as a “Partition Descriptor”. An LSN of “35” is defined as a“Logical Volume Descriptor”. An LSN of “36” is defined as an“Unallocated Space Descriptor”. An LSN of “37” is defined as a“Terminating Descriptor”. The “Primary Volume Descriptor” defined by theLSN of “32” is a volume descriptor defined in the Universal Disk Format(UDF). The “Implementation Use Volume Descriptor” defined by the LSN of“33” is a volume descriptor for a logical system. The “PartitionDescriptor” defined by the LSN of “34” is a partition descriptor. The“Logical Volume Descriptor” defined by the LSN of “35” is a logicalvolume descriptor. The “Unallocated space Descriptor” defined by the LSNof “36” is an allocated space descriptor. The “Terminating Descriptor”defined by the LSN of “37” indicates the termination of the descriptor.Subsequent to this, LSNs from “38” to “47” are defined as “TrailingLogical Sectors”.

[0109] LSNs from “48” to “63” are defined as reserved VDS areas. Thereserved VDS areas are made to be identical to main VDS area, and areused as backups when information cannot be read from the main VDS areas.

[0110] The “Logical Volume Integrity Descriptor” defined by the LSN of“64” is an integrity descriptor for controlling various kinds of faultinformation generated in the logical volume. The “TerminatingDescriptor” defined by the LSN of “65” indicates the termination of thedescriptors.

[0111] The “Anchor Volume Descriptor Pointer” defined by the LSN of“256” is an anchor point for indicating the position of the main VDSarea. The LSN of “257” and thereafter indicate the ISO 9660 filestructure such as a “Path Table” for indicating the path for reachingthe aimed file, a “Root Directory”, and the like. Subsequent to theseareas, information standardized by the UDF, for example, the UDF filestructure including a “File Set Descriptor” and a “File Entry” isindicated. The area subsequent to this area is defined as an UDF/ISOfile storing area in which computer data, video data, and the like arerecorded. The last LSN is defined as a second anchor point. The secondanchor point is made to be identical to the anchor point defined by theLSN of “256”, and is used as a backup when the anchor point defined bythe LSN of “256” cannot be read.

[0112] An UDF logical volume space is allocated starting from theposition with the logical sector number p for indicating the UDF filestructure. A logical block number q is allocated starting from theposition with the logical sector number p.

[0113]FIG. 18 shows a directory structure. Video data is stored into the“VIDEO_TS” directory. Audio data is stored into the “AUDIO TS”directory. Computer data is stored into the computer data directory. Thedirectory with an extension of “IF0” is a directory related toreproduction and control information. The extension of “V0D” is anextension related to video data. The extension of “A0D” is an extensionrelated to audio data. The extension of “BUP” is used as a backup.

[0114]FIG. 19 shows a structure of a disk reproducing apparatus 60 forreproducing a DVD 50. The DVD 50 is rotated at a predetermined speed bya spindle motor section 66. The spindle motor section 66 is driven insuch a manner as to control the DVD 50 to rotate at a predeterminedspeed, based on a frame synchronous signal SF from a read-channel/servocontrolling section 63 which will be described later.

[0115] The DVD 50 is irradiated with a light beam in a controlled lightamount from an optical pickup 61 of the disk reproducing apparatus 60.The light beam reflected by the DVD 50 is irradiated to a photodetectingsection (not shown) of the optical pickup 61. Based on the reflectedlight beam, the photodetecting section performs photoelectric conversionand current-voltage conversion to produce a voltage signal at a signallevel corresponding to the light amount of the reflected light beam, andsupplies the resultant voltage signal to an RF amplifying section 62.

[0116] The RF amplifying section 62 produces a read signal SRF, atracking error signal STE and a focus error signal SFE using the voltagesignal from the optical pickup, and supplies the resultant signals tothe read-channel/servo controlling section 63.

[0117] The read-channel/servo controlling section 63 produces a focuscontrol signal SFC for controlling an object lens (not shown) of theoptical pickup 61 in such a manner that the laser beam focuses on theposition in the recording layer of the DVD 50, based on the focus errorsignal SFE supplied thereto, and supplies the resultant focus controlsignal SFC to the driver 64. The read-channel/servo controlling section63 also produces a tracking control signal STC for controlling theobject lens of the optical pickup 61 in such a manner that the lightbeam is irradiated to the center position of the desired track, based onthe tracking error signal STE supplied thereto, and supplies theresultant tracking control signal STC to a driver 64.

[0118] The driver 64 produces a focus drive signal SFD, based on thefocus control signal SFC, and also produces a tracking drive signal STD,based on the tracking control signal STC. Thus-produced focus drivesignal SFD and tracking drive signal STD to an actuator (not shown) ofthe optical pickup 61, and as a result of this, the position of theobject lens is controlled in such a manner that the light beam focusesat the center position of the desired track.

[0119] The read-channel/servo controlling section 63 performs asymmetrycorrection and binarization for the read signal SRF supplied thereto,and converts the read signal SRF into a digital signal to produce a datasignal DRF, and then supplies the resultant data signal DRF to a dataprocessing section 65. The read-channel/servo controlling section 63also performs production of a clock signal CKRF synchronous with thedigital data obtained as a result of conversion, and detection of aframe synchronous signal, and then, supplies thus-produced clock signalCKRF to the data processing section 65, and supplies the framesynchronous signal SF to the spindle motor section 66.

[0120] The read-channel/servo controlling section 63 also produces athread control signal SSC for controlling the optical pickup 61 to shifttoward a radial direction of the DVD 50 in order to prevent the laserbeam from being irradiated beyond the tracking control range, andsupplies the resultant thread control signal SSC to a thread section 67.The thread section 67 drives a thread motor so as to control the opticalpickup 61 to shift toward a radial direction of the DVD 50.

[0121] The data processing section 65 performs 8/16 demodulation for thedata signal DRF, and also performs error correction by a reed-solomoncode using a part of the memory area of a RAM (Random Access Memory) 68as a work area. The data signal after error correction is stored into acash area which is a part of the memory area of the RAM 68, and then, issupplied as a reproduction data signal RD to the computer apparatus andthe like via an interface section 69 in compliance with the ATAttachment Packet Interface (ATAPI) standards for example. The dataprocessing section 65 reads positional information for indicating theposition on the optical disk from the data signal DRF, and supplies thepositional information to a controlling section 70. In the case wherethe data processing section 65 reads fault positional informationrecorded in the DVD 50, the fault positional information is supplied tothe controlling section 70.

[0122] To the controlling section 70, a ROM 71 is connected. Thecontrolling section 70 processes a command from the computer apparatusbased on the program for operation control stored in the ROM 71, andcontrols operations of each of the sections in the disk reproducingapparatus 60. For example, when there is an access request from thecomputer apparatus by the ATAPI command by use of the logical address,the controlling section 70 converts the logical address into a physicaladdress, referring to the fault positional information about the opticaldisk supplied from the data processing section 65. In this case, thecontrolling section 70 simultaneously drives the optical pickup 61 insuch a manner that access to the position of the physical addressobtained as a result of conversion is made, by use of the informationfor indicating the position on the optical disk supplied form the dataprocessing section 65.

[0123] Next, a data reproducing operation in the disk reproducingapparatus 60 will be described with reference to FIG. 20. When a commandfor requesting data written in the DVD 50 is supplied from the computerapparatus, the controlling section 70 in the disk reproducing apparatus60 identifies whether or not the supplied command is effective in StepST41. When the command is wrong or is identified as a command whichcannot be processed and therefore as an ineffective command, theprocedure proceeds to Step ST42 where the ineffectivenss of the commandis announced to the computer apparatus. Then, the processing isterminated. When the command is effective, the procedure proceeds toStep ST43.

[0124] In Step ST43, it identified whether or not the data requested inresponse to the command is stored in the RAM 68. When it is identifiedthat the data is stored, the procedure proceeds to Step ST44 where therequested data is transmitted from the RAM 68 to the computer apparatus.Then, the processing is terminated. When it is not identified that thedata is stored, the procedure proceeds to Step ST45.

[0125] In Step ST45, the number of times N of retries is set to “0”,Then, the procedure proceeds to Step ST46 where an interruption isperformed. In the interruption in Step ST46, the data is read in unitsof 16 sectors, and the required data is read from the disk via theoptical pickup 61 and the RF amplifying section 62. At the same time,the data processing section 65 performs an error correction for the datasignal DRF supplied from the read channel/servo controlling section 63.By use of the error detection code (EDC) which is added to each of thesectors, it is identified whether or not the error correction has beenperformed correctly. Then, the interruption is terminated. The number oftimes N of retries indicates how many times the procedure in Step ST46has been repeated because the correct data cannot be read.

[0126] In Step ST47, the physical sector number for example in the firstsector is stored in the register in the controlling section 70 as IDinformation. At the same time the results of identification which hasbeen performed by use of the EDC is stored in the register as well.Then, the procedure proceeds to Step ST48. In Step ST48, it isidentified whether or not a detection flag for indication that the diskhas been identified as a DVD-video disk is set. If the detection flag isnot set because the identification whether or not the disk is aDVD-video disk is still not performed, or if the detection flag is notset because the disk has not been identified as a DVD-video disk as aresult of the identification, the procedure proceeds to Step ST49 wherethe disk identification for identifying whether or not the disk is aDVD-video disk is performed. When the identification result flag is setbecause the disk has been identified as a DVD-video disk, the procedureproceeds to Step ST 50.

[0127]FIG. 21 is a flow chart showing a disk identification in StepST49. In Step ST61, it is identified whether or not the stored IDinformation has the physical sector number of “30100h” which indicatesthe LSN of “256”, and also whether or not the error correction has beencompleted correctly, based on the result of the identification using theEDC. When the ID information indicates the physical sector number of“30100h”, that is, data of 16 sectors is read in the state where theinformation of “Path Table” is included, and also the error correctionhas been completed correctly, the procedure proceeds to Step ST 62. Whenthe ID information does not indicate the physical sector number of“30100h”, or the error correction has not been completed correctly, theidentification is terminated.

[0128] In Step ST62, the data for indicating the directory informationis read from the data of the sector including the “Path Table” of thedata stored in the RAM 68. Then, it is identified whether or not thecharacter for indicating the directory of video data has been detected.

[0129]FIG. 22 is a dump list indicating a part of data of 16 sectorswhich has been read from the position with the LSN of “256” and has beenstored into the RAM 68. In Step ST62, the data is read from the 31stsector data (at the address “1Eh” assuming that the address of the firstdata is “0h”) with the LSN of “257” (with the physical sector number of“30101h”) which includes the “Type L Path Table”. Then, it is identifiedwhether or not a predetermined character string, for example, acharacter string “VIDEO_TS” (with data of 56 49 44 45 4F 5F 54 53) whichmakes it possible to identify the video data as being recorded has beendetected. When the character string has been detected, the procedureproceeds to Step ST 66. When the character has not been detected, theprocedure proceeds to Step ST63.

[0130] In Step ST63, the data is read from the 47th sector (at theaddress “2Eh” assuming that the address of the first data is “0h”) whichalso has been used in Step ST 62. Then, it is identified whether or nota predetermined character string has been detected. When the characterstring has been detected, the procedure proceeds to Step ST66. When thecharacter string has not been detected, the procedure proceeds to StepST64.

[0131] As described above, in the steps ST 62, 63 detection of thecharacter string is performed at different positions in an identicalsector. In this manner, even when no audio data is recorded andtherefore the position of the character string of “VIDEO_TS” is set to“AUDIO_TS” shown in FIG. 22, the character string can be reliablydetected.

[0132] Next, in Step ST64, data is read from a predetermined position inthe sector which includes the “Path Table” of the data stored in the RAM68 and is different from the sectors used in Steps ST62, ST63. Then, itis identified whether or not a predetermined character string has beendetected. For example, the data is read from the 31st sector data withthe LSN of “258” (with the physical sector number of “30102h”) whichincludes the “Type M Path Table”. Then, it is identified whether or nota predetermined character string has been detected. When the characterstring has been detected, the procedure proceeds to Step ST66. When thecharacter string has not been detected, the procedure proceeds to StepST65.

[0133] In Step ST65, the data is read from the 47th sector which alsohas been used in Step ST64. Then, it is identified whether or not apredetermined character string has been detected. As described above,detection of the character string is performed for different sectorsbetween Steps ST62, 63 and Steps ST64, 65. In this manner, the characterstring can be detected more reliably.

[0134] When the character string has been detected in this Step ST65,the procedure proceeds to Step ST66. When the character string has notbeen detected, this means that no character string which makes itpossible to identify the video data as being recorded is detected. Inthis case, the disk is identified as not being a DVD-video disk and theprocessing is terminated.

[0135] When the procedure proceeds from Steps ST62 |ST65 to Step ST66,the character string of “VIDEO_ST” which makes it possible to identifythe video data as being recorded is detected. In this case, the diskfrom which the data has been read is identified as a DVD-video disk, andthe identification result flag is set. Then, the identification isterminated.

[0136] As described above, when the video data is recorded, the data isread from the sector into which the character string which makes itpossible to identify the video data as being recorded is recorded. Then,the character string for indicating that this video data is included isdetected. Based on the result of the detection, the identification as towhether or not the disk is a DVD-video disk can be made correctly.

[0137] In the above-described case, the detection of the characterstring is started from 31st or 47th sector, because the character stringwhich makes it possible to identify the video data and the like as beingrecorded is recorded at a predetermined position in plural sectors eachincluding the “Path Table”. If the position of the character string isnot fixed, the data can be read from the leading end of the sector, andit is identified whether or not this is data of the character string forindicating that the video data is recorded. In addition, the sector fromwhich the data is stored is not limited to the sector including the“Path Table”, but may be read from any other sectors as far as they havedata of the character string for indicating that the video data isrecorded.

[0138] When the identification is terminated, the procedure proceedsfrom Step ST49 to Step ST52 as shown in FIG. 20. When the procedureproceeds from Step ST48 to Step ST50, in Step ST50, it is identifiedwhether or not the number of times N of retries becomes larger than thepredetermined number of times NR. When the number of times N of retriesbecomes larger than the predetermined number of times NR, the procedureproceeds to Step ST51. When the number of times of retries N is notlarger than the predetermined number of times NR, the procedure proceedsto Step ST52.

[0139] In Step ST51, based in the ID information stored in Step ST47, itis identified whether the data read from the DVD-video disk is data ofinformation about reproduction or data for reproducing images and thelike. When data of information about reproduction, for example, data ofvolume descriptors or file structure is recorded within the range of thephysical sector numbers of “3000h” to “kh”, it is possible to identifywhether the read data is data of information about reproduction or datafor reproducing images and the like, depending on whether or not thephysical sector number of “RSh” of the stored ID information is largerthan the sector number of “kh”. When the physical sector number of “RSh”of the stored ID information is not larger than the physical sectornumber of “kh”, the procedure proceeds to Step ST52. When the physicalsector number of “RSh” of the stored ID information is larger than thephysical sector number of “kh”, this means that the data stored in theRAM 68 is data for reproducing images and the like stored in theDVD-video disk, and the number of times of retries becomes larger thanthe predetermined number of times NR. In this case, the requested datais read from the RAM 68 in Step ST51, and is supplied into the computerapparatus. Then, the processing for the command is terminated.

[0140] In Step ST52, based on the result of identification using theEDC, it is identified whether or not the error correction has beencompleted, as well as whether or not the error correction has beenperformed correctly. When the error correction has not been completedcorrectly, the procedure proceeds to Step ST53. When the errorcorrection has been completed correctly, this means that the data storedin the RAM 68 is correct data. In this case, the data requested inresponse to the command from the computer apparatus is read from the RAM68 in step ST 54, and is supplied to the computer apparatus. Then, theprocessing for the command is terminated.

[0141] In step ST53, it is identified whether or not the number of timesN of retries becomes larger than the predetermined number of times NS.When the number of times N of retries is not larger than thepredetermined number of times NS, the procedure proceeds to Step ST55where “1” is added to the number of times N of retries to produce a newnumber of times of retries. Then, the procedure returns to Step ST 46where the data is again read from the disk. When the number of times Nof retries is larger than the predetermined number of times NS, the datacannot be read correctly, and the disk is not a DVD-video disk. In thiscase, an error is announced to the computer apparatus in Step ST56, andthen the processing for the command is terminated.

[0142] As described above, in the processings shown in FIGS. 20 and 21,when a request for reading data from the computer apparatus is made andthe data of 16 sectors is read from the physical sector number of“30100h” in which data of information about reproduction is recorded, itis automatically identified whether or not the disk from which the datahas been read is a DVD-video disk in which video data is recorded. Whenthe disk is identified as a DVD-video disk in which video data isrecorded and the data is read at the number of times larger than thepredetermined number of times NR, if it is identified that the errorcorrection for the read data cannot be completed correctly, the data issupplied to the computer apparatus. When the disk is not identified as aDVD-video disk in which video data is recorded and the data is read atthe number of times larger than the predetermined number of times NR, ifit is identified that the error correction for the read data cannot becompleted correctly, an error is announced to the computer apparatus.

[0143] Therefore, it is possible to reproduce images withoutinterruption by reducing the predetermined number of times NR at thetime when the disk is identified as a DVD-video disk to be smaller thanthe predetermined number of times NS. Even if the disk is not identifiedas a DVD-video disk or the read data is control data, the probability ofreading data correctly can be increased by increasing the predeterminednumber of times NS. In addition, an error is announced when the datacannot be read correctly. In this manner, in the case of the DVD-ROMdisk for example, only correct data can be supplied to the computerapparatus.

[0144] In the above-described embodiment, the requested data is read inresponse to the supplied command. When the detection flag is not set,the disk identification is automatically performed if the data read inthe disk identification in Step ST49 is data of 16 sectors counted fromthe physical sector number of “30100h”. Alternatively, the data of 16sectors counted from the physical sector number of “30100h” is read whenthe disk is mounted to the disk reproducing apparatus to makeidentification whether or not the disk is a DVD-video disk, and theresult of the identification is stored. In this case, in Step ST48, thestored identification result is used. In this manner, it is alsopossible to supply data in response to the command, as is the casedescribed above.

[0145] Furthermore, in the embodiment described above, the operation ofsupplying data is switched based on the result of the identification ofthe disk. Alternatively, the result of the identification of the diskmay be utilized in other operations.

[0146] It is assumed here that the control on the rotation of thespindle motor is switched based on the result of the identification ofthe disk. For example, when the disk is identified as a DVD-video disk,this disk is intended for video reproduction and there is no need forreading the data at high speed. Therefore, the disk is rotated at anormal speed, thereby preventing an increase in power consumption anddecreasing the sounds created by the operations of the disk apparatus.When the compact disk is not identified as a DVD-video disk, the data isread in the state where the disk is rotated at a speed higher than anormal speed, thereby increasing the data transition rate. As a result,the data can be efficiently processed in the computer apparatus.

[0147] It is possible to switch the amount of data which is readbeforehand based on the results of disk identification. As to aDVD-video disk, there are many cases where the data recorded for use inreproducing images and the like is sequentially read. Therefore, whenthe disk is identified as a DVD-video disk, the amount of data which isread beforehand is increased. In this manner, the read data can beefficiently processed, and in addition, the interruption of the imagesfor example can be prevented.

[0148] On the other hand, as to the DVD-ROM in which computer data isstored, there are many cases where the data is read at random. In suchcases, reading of the data beforehand may not be effective. There arealso some cases where various control parameters are required in orderto shorten the access time. For these reasons, the amount of data whichis read beforehand is reduced. As a result, the data can be readefficiently, without reading unnecessary data. Furthermore, byperforming the retry in the state where the rotation speed of the diskand the conditions of reading data are changed, the probability ofreading the data in a correct manner can be increased.

[0149] The control on the operations based on the result ofidentification of the disk has been illustrate only for the purpose ofexemplification, and the present invention is not limited to theoperation control described above.

INDUSTRIAL APPLICABILITY

[0150] As has been described above, the method for identifying opticaldisks, method for reproducing optical disks, and an optical diskapparatus according to the present invention are useful in the casewhere plural kinds of optical disks in which data with differentcontents from each other are reproduced, and are especially useful inthe case of reproducing optical disks in which data required to havehigh reliability such as computer data are stored, and optical disks inwhich data putting priorities on keeping transmission rate to keepcontinuity are recorded such as video data.

1. A method for identifying optical disks, comprising the step of: in astate where each the optical disks is reproduced, performingidentification of the optical disk, based on whether or not data at apredetermined position on a logical format has predetermined data.
 2. Amethod for identifying optical disks according to claim 1, wherein eachof the optical disks is reproduced in a predetermined sequence, and theidentification of the optical disk is performed when the data at thepredetermined position on the logical format is reproduced.
 3. A methodfor identifying optical disks according to claim 1, wherein the data atthe predetermined position is data in a unit of block recorded in theoptical disk, and the predetermined data is data of a error correctioncode completed within the block.
 4. A method for identifying opticaldisks according to claim 1, wherein the data at the predeterminedposition is data in a predetermined file structure recorded in each ofthe optical disks, and the predetermined data is data related tocontends of the recorded data.
 5. A method for reproducing opticaldisks, comprising the steps of: performing identification of each of theoptical disks based on whether or not data at a predetermined positionon a logical format obtained by reproducing the optical disk haspredetermined data; and controlling a reproducing operation based on aresult of the identification.
 6. A method for reproducing optical disksaccording to claim 5, wherein, when an error is detected in the dataobtained by reproducing each of the optical disks, a processing forresponding to the error detection is switched based on the result of theidentification.
 7. A method for reproducing optical disks according toclaim 6, wherein retry for reading data from each of the optical disksagain is performed in the processing for responding to the errordetection, and a number of times of the retries or a period of time forthe retries performed until correct data is obtained is switched basedon the result of the identification.
 8. A method for reproducing opticaldisks according to claim 6, wherein, when the data in which an error hasbeen detected is control data related to an operation, the switching ofthe processing for responding to the error detection is cancelled.
 9. Amethod for reproducing optical disks according to claim 5, wherein aspeed of reading data from each of the optical disks is switched basedon the result of the identification.
 10. A method for reproducingoptical disks according to claim 5, wherein an amount of data read fromeach of the optical disks beforehand is switched based on the result ofthe identification.
 11. An optical disk apparatus comprising: datareading means for, in a state where each of optical disks is reproduced,reading data recorded therein; and control means for identifying theoptical disk based on whether or not data which has been obtained by thedata reading means and is located at a predetermined position on alogical format has predetermined data, and for performing control on anoperation in accordance with a result of the identification.
 12. Anoptical disk apparatus according to claim 11, comprising: errordetection means for detecting an error of the data obtained by the datareading means, wherein when the error is detected by the error detectionmeans, the control means switches processing for responding to the errordetection based on the result of the identification.
 13. An optical diskapparatus according to claim 11, wherein the control means controls thedata reading means based on the result of the identification in such amanner as to switch a speed at which data is read from each of theoptical disks.
 14. An optical disk apparatus according to claim 11,wherein the control means controls the data reading means in such amanner as to switch an amount of data to be read forehand from each ofthe optical disks based on the result of the identification.